Measuring systems designed as a polarimeter can measure different optical polarization properties of a sample. In the simplest case the changes in the oscillation plane of linearly polarized light, known as optical rotation and caused by the optical activity of the sample, is measured. However, also further optical polarization properties of the sample can be measured, right up to a full determination of the so-called Müller matrix, which is the transformation matrix for the Stokes vector. As is known, the Stokes vector describes the polarization state of an electromagnetic wave. The Müller matrix characterizes the sample in question in terms of its interaction with the electromagnetic wave. More particularly, the Müller matrix describes the change in the polarization state of an electromagnetic wave, for example with a reflection at a sample boundary or with a transmission of the electromagnetic wave through the sample.
A polarimeter for measuring the optical polarization properties of a sample comprises a mechanical support structure on which the components of relevance for measuring are mounted by means of suitable holders. These components comprise a light source, which emits collimated measuring light along an optical axis of the polarimeter. For producing the collimated light, diaphragms and/or lenses can be used. The measuring light passes through a polarization state generator (PSG) which produces a defined polarization state of the measuring light. The measuring light then penetrates through the sample to be examined. In the case of a liquid sample this is situated in a cuvette. The polarization state of the measuring light is changed with passing through the sample and is detected by means of a polarization state analyzer (PSA).
In order to achieve a measuring accuracy, the mechanical stability of the structure of a polarimeter is subject to the highest requirements. More particularly, torsions between the precision-determining elements PSG and PSA must be avoided. This can be achieved by a correspondingly solid mechanical support structure on which there are mounted components that determine the measuring accuracy of the polarimeter. A solidly designed support structure results in the polarimeter not only being particularly heavy but also having relative large structural dimensions.
There may be a need for optimizing the structure of an optical measuring system so that it can be simply produced in a compact design.